PLS, I NEED TO BE GUIDED ON HOW TO WRITE A SIMPLE PROGRAM IN BASIC THAT WOULD PROMPT 3 LEVELS OF AUTHENTICATION WHEN UNAUTHORISED LOG-ON IS EFFECTED.

You are not going to be able here to get detailed help on the program code, as there are many, many versions of BASIC language.

What I would do, if you have not begun, is to write a logic pattern (flowchart) of what you want to do. Doing that will allow you to compartment the code writing to independent steps.

To write a simple program in BASIC that prompts for three levels of authentication when an unauthorized login is detected, you can follow these general steps:

1. Define the goal and logic of your program: Start by determining what exactly you want your program to do. Specify the authentication levels and conditions for each level.

2. Plan your program's structure: Create a flowchart or outline the sequence of steps your program should follow. Divide the tasks into manageable chunks to make your code easier to write and understand.

3. Choose a version of BASIC: Decide which version or dialect of the BASIC programming language you want to use. Some popular versions include QBASIC, Visual Basic, FreeBASIC, and GW-BASIC.

4. Set up the initial program structure: Begin by opening the basic programming environment of your chosen version. Declare any necessary variables and initialize them accordingly.

5. Implement the authentication checks: Write the code for each level of authentication, using appropriate logic and syntax for your chosen BASIC version. Here are some general steps for each level:

a. Level 1 authentication: Prompt the user for their login credentials and compare them against predetermined values. If the login is unauthorized, proceed to the next authentication level.

b. Level 2 authentication: Implement a more secure authentication method, such as a PIN or additional password. Repeat the same process as in Level 1 for this level of authentication. If the login is still unauthorized, proceed to the next level.

c. Level 3 authentication: Add an additional layer of authentication, such as biometric authentication or a security token. Repeat the previous steps for this level.

6. Implement actions for unauthorized log-on: If all three levels of authentication fail, perform the necessary actions defined by your program, such as logging the incident, displaying an error message, or terminating the program.

7. Test and debug: Run your program and test it with various scenarios, including authorized and unauthorized logins. Check for any logical errors, syntax problems, or unexpected behavior. Debug and refine your code as necessary.

Remember that the specific implementation details will depend on the version of BASIC you choose, the platform you're running it on, and any additional requirements or constraints. Consult the documentation or resources available for your chosen BASIC version for more specific instructions on programming syntax and features.